Steel and refining
Fluid catalytic cracking
Also known as FCC, fluid catalytic cracker, cat cracker.
Fluid catalytic cracking (FCC) is the central process of a fuels refinery, cracking heavy hydrocarbons (vacuum gas oil, residue) into lighter products — primarily gasoline, with valuable C₃–C₄ olefin streams as co-products. The reaction takes place at ~520 °C over a fluidised bed of zeolite catalyst circulated between a riser-reactor and a regenerator.
Cleaning targets in the FCC complex
- Riser-reactor cyclones — separate spent catalyst from hydrocarbon vapour
- Regenerator primary and secondary cyclones — separate regenerated catalyst from flue gas
- Third-stage separator (TSS) — recovers catalyst fines from flue gas
- CO boiler — burns regenerator flue-gas CO for energy recovery
- Catalyst fines hopper — fine catalyst recovered from the gas-cleaning train
Sonic-horn fit
Refinery FCC units are demanding applications: high temperature, abrasive catalyst, continuous 24/7 operation, very high economic stakes per outage hour. Sonic horns on the third-stage separator and on catalyst-fines hoppers help maintain flue-gas-cleaning efficiency and avoid the unplanned slowdowns associated with hopper bridging.
Related terms
Related terms
- FCC regeneratorThe FCC regenerator burns coke deposits off spent cracking catalyst, restoring activity and producing high-temperature flue gas for downstream energy recovery.
- Third-stage separatorA third-stage separator recovers very fine catalyst fines from the FCC regenerator flue gas using high-efficiency cyclones. Pluggage of the underflow leg is a chronic operational issue.
- Cyclone separatorA cyclone separator removes particulate from a gas stream by centrifugal force. Wall build-up and re-entrainment from the dipleg are the dominant operational issues.
- Sonic hornA sonic horn is a pneumatically-driven low-frequency sound emitter (typically 60–400 Hz at 140–180 dB SPL) used to dislodge particulate fouling from boilers, ESPs, baghouses and process vessels.